Black soap films (BSFs) have been prepared from the aqueous solution of cetyltrimeth-ylammonium bromide (CTAB) containing methyl orange (MO). The dynamic process ofthe formation of the BSFs was examined by electronic ...Black soap films (BSFs) have been prepared from the aqueous solution of cetyltrimeth-ylammonium bromide (CTAB) containing methyl orange (MO). The dynamic process ofthe formation of the BSFs was examined by electronic absorption and FT-IR spectroscopies.The thickness of the aqueous core of the BSF was found to decrease with the increase of MOconcentration, altering from common BSFs to Newton ones. The spectral features of CH_2stretching vibrations of methylene chain and the π--π~* absorption of MO show that boththe CTAB and MO molecules are in oriented liquid crystalline state in the two types of theBSFs. Theoretical consideration of Raman scattering activity has been made of uniaxiallyoriented molecules. From the polarized resonance Raman measurements of the BSFs, it wasknown that the long axes of the MO molecules were tilted with a large angle of about 80°with the surface normal in the two types of the BSFs.展开更多
Recently, the structure of the black soap film(BSF)has been found to be similar to biomembrane, and therefore has been used as a model to study the functions, properties and structures of the biomembrane.
Dye molecule brilliant yellow (BY) has been used as an acid-base probe in the study of the resonance Raman spectra of three kinds of microenvironments of the black soap film (BSF) containing BY, the BY-CTAB micellar s...Dye molecule brilliant yellow (BY) has been used as an acid-base probe in the study of the resonance Raman spectra of three kinds of microenvironments of the black soap film (BSF) containing BY, the BY-CTAB micellar solution, and the aqueous BY solution under various pH conditions. It has been revealed that BY bound to the sandwich interface of the BSF and that to the micellar interface show similar spectral changes, but the former owns the character of coexistence of acidic and basic structures in a relatively large range of pH values (neutral to basic). Further investigations have demonstrated that BSF exhibits the buffer effect that the pH value of the aqueous core is insensitive to the pH change of the bulk solution.展开更多
In gas-liquid mass transfer processes,Marangoni convection may occur due to the surface tension gradient produced by mass transfer near the interface.With a falling soap film tunnel and the Schlieren optical method,th...In gas-liquid mass transfer processes,Marangoni convection may occur due to the surface tension gradient produced by mass transfer near the interface.With a falling soap film tunnel and the Schlieren optical method,the Marangoni convection patterns along the film surface were observed directly in the desorption process of acetone from the falling soap film.The Schlieren images showed the regular roll convection in the thin falling soap film during the acetone desorption.The hydraulic characteristics were determined experimentally by measuring the variation of acetone concentration in the film and the surface tension of the soap liquid.The results show that the acetone concentration gradient vertical to the falling direction is very small because the thickness of the soap film is in the order of 10-6 m.The variation of acetone concentration along the falling film is large,so there is a significant surface tension gradient,resulting in the Marangoni roll convection.The experimental results and a qualitative analysis may be helpful to understand the mechanism of Marangoni convection near the interface in the mass transfer.展开更多
基金Project supported by the National Natural Science Foundation of China.
文摘Black soap films (BSFs) have been prepared from the aqueous solution of cetyltrimeth-ylammonium bromide (CTAB) containing methyl orange (MO). The dynamic process ofthe formation of the BSFs was examined by electronic absorption and FT-IR spectroscopies.The thickness of the aqueous core of the BSF was found to decrease with the increase of MOconcentration, altering from common BSFs to Newton ones. The spectral features of CH_2stretching vibrations of methylene chain and the π--π~* absorption of MO show that boththe CTAB and MO molecules are in oriented liquid crystalline state in the two types of theBSFs. Theoretical consideration of Raman scattering activity has been made of uniaxiallyoriented molecules. From the polarized resonance Raman measurements of the BSFs, it wasknown that the long axes of the MO molecules were tilted with a large angle of about 80°with the surface normal in the two types of the BSFs.
基金Project supported by the National Natural Science Foundation of China.
文摘Recently, the structure of the black soap film(BSF)has been found to be similar to biomembrane, and therefore has been used as a model to study the functions, properties and structures of the biomembrane.
基金Project supported by a grant for the major research project from the State Science and Technology Commission.
文摘Dye molecule brilliant yellow (BY) has been used as an acid-base probe in the study of the resonance Raman spectra of three kinds of microenvironments of the black soap film (BSF) containing BY, the BY-CTAB micellar solution, and the aqueous BY solution under various pH conditions. It has been revealed that BY bound to the sandwich interface of the BSF and that to the micellar interface show similar spectral changes, but the former owns the character of coexistence of acidic and basic structures in a relatively large range of pH values (neutral to basic). Further investigations have demonstrated that BSF exhibits the buffer effect that the pH value of the aqueous core is insensitive to the pH change of the bulk solution.
文摘In gas-liquid mass transfer processes,Marangoni convection may occur due to the surface tension gradient produced by mass transfer near the interface.With a falling soap film tunnel and the Schlieren optical method,the Marangoni convection patterns along the film surface were observed directly in the desorption process of acetone from the falling soap film.The Schlieren images showed the regular roll convection in the thin falling soap film during the acetone desorption.The hydraulic characteristics were determined experimentally by measuring the variation of acetone concentration in the film and the surface tension of the soap liquid.The results show that the acetone concentration gradient vertical to the falling direction is very small because the thickness of the soap film is in the order of 10-6 m.The variation of acetone concentration along the falling film is large,so there is a significant surface tension gradient,resulting in the Marangoni roll convection.The experimental results and a qualitative analysis may be helpful to understand the mechanism of Marangoni convection near the interface in the mass transfer.
